Wireless receiving system.



L. ESPENSCHIED.

WIRELESS RECEIVING SYSTEM.

APPLICATION FILED SEPT-23,1915- Patented Apr. 24,1917.

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ZZspensm/Z'd L. ESPENSCHIED.

WI RELESS secnvmo SYSTEM. APPLICATION FILED SEPT-23,1915- 1,223,376.Patented Apr. 24, 1917.

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I 5 1 Q I j I 5 Q Q INVENTOI? LEspenschied WWW A ITOR/VEY LLOYDESPENSCHIED, OF BROOKLYN,

NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, ACORPORATION OF NEW YORK.

WIRELESS RECEIVING SYSTEM.

To all whom it may concern:

Be it known that I, LLOYD -ESPENSCHIED, residing at 1369 Dean street,Brooklyn, in the county of Kings and State of New York, have inventedcertain Improvements in Wireless Receiving Systems, of which thefollowing is a specification.

This invention relates to a wireless signaling system, and moreparticularly to a system for the reception of wireless signals. Itsobject is to provide a receiving system in which thereceiving instrumentshall be protected from disturbing oscillations, such as those duetoatmospheric or static disturbances, which might interfere with theeflicient reception of signals. The invention finds its use inconnection with a wireless telegraph or telephone system.

It is well known to those acquainted with the art that atmospheric orstatic interference constitutes a very serious menace to thesatisfactory reception. of-wireless messages and that the elimination ofsaid interference is a problem of great difiiculty. This difiicultyinheres in the fact that the frequency to which the receiving system istuned, and is therefore most responsive, is very closely the same as thefrequency of the natural oscillations set up by the incidence of anatmospheric disturbance on the receiving antenna. The naturaloscillations are therefore of substantially the frequency to moststrongly afiect the receiving device, andcannot be eliminated by tuningas can persistent disturbances from a foreign station.

This invention contemplates an arrangement by which the receivingdevice, in addition to being operatively connected to the antennacircuit proper, is also connected to an auxiliary antenna circuit, suchconnections being made through suitable translating means, such asdetectors, for rendering the receiving device unresponsive to disturbingoscillations simultaneously occurring in the two antenna'circuits. I

The invention will be best understood by reference to the accompanyingdrawings in which, 'Figures 1, 2 and 3 are diagrams showing threedifferent embodiments of my invention.

Referring to Fig. 1,'it will be observed that the'particularorganization shown consists of a receiving system properand'a similarauxiliary system having a common receiving device, the latter beingconven- Specification of Letters Patent.

Patented Apr. 24, 1917.

Application filed September 23', 1915. Serial No. 52,260.

tionally represented by a telephone receiver 14. he component parts ofthe auxiliary system, whose function will hereinafter be fully setforth, are similar to the corresponding elements of the receiving systemproper. It will therefore be understood that, so far as the physicalstructures are concerned, the same description applies to the auxiliarysystem as to the receiving system proper.

In the receiving system proper, a receiving antenna 1, contains a tuningcondenser 2 and a coupling coil 3. An oscillation circuit 4 contains atuning condenser 6 and a coupling coil 5, whereby it is loosely coupledto the antenna. Circuit 4 is tuned to the same frequency, or wavelength, as the antenna 1, that is to the wave length of the signals itis desired to receive from the sending station (not shown). In theauxiliary system, a circuit 4 is similarly loosely coupled to anauxiliary antenna 1 and tuned to the same Wave length as said antenna 1.This wave length is, however, different from the wave length to whichthe elements 1 and 4 are tuned. Bridged across the condenser 6 is theinput side of a detector, preferably of the vacuum tube type,conventionally represented by 8. I 8' is the corresponding detectorof-the auxiliary receiving system. The output side of the detector 8 isclosed through an impedance coil 9 and a non-inductive resistanceelement 10.

Bridged across the resistance element 109- is the input side of anamplifier 11, preferably of the vacuum tube type. side of said amplifieris closed through an impedance coil 12 and a non-inductive *resistanceelement 13. The telephone receiver 14 is connected across bothnon-inductive resistance elements 13 and 13','in such a manner that nocurrent flows through 14 if the potential drop across resistances 13 and13 are equal. Condensers 15, '15 prevent the flow of steady directcurrent through the receiver 14. Theauxiliary antenna may contain aresistance element 17, whereby its natural damping may be adjusted. v

The operation of the organization shown in Fig. 1 may now be described.As hereinbefore stated, the antennastructure 1 and the circuit 4 aretuned to the Wave length of a the sending station, while thecorresponding parts 1' and'4 of the auxiliary system are tuned to adifierent wave length. Cir- The output and oscillation circuits,

cuit 4, therefore, oscillates strongly in response to theelectromagnetic waves from the sending station to which it is tuned,while circuit 4 responds very weakly thereto. It is evident, therefore,that the oscillating potential impressed across the terminals ofresistance 13 is very large compared to that across resistance 13, andtherefore an oscillating current, corresponding to the received signals,flows in the receiver 14. Said oscillatory current flowing in thereceiver 14 will not be of high or radio-frequency as are theoscillations in the antenna but owing to the translating action ofdetector 8 and the choking action of impedance coil 9, it will be of lowor audio-frequency corresponding in telegraphy to the group frequency ofsaid high frequency oscillations, or in telephony to the modulationfrequency of said high frequency oscillations. In fact said oscillatorycurrent in the receiver 14 will be substantially independent of thefrequency of the radlo-frequency oscillations operating on the inputside of the detector and will depend only on the amplitude and dampingfactor or modulation of said radio-frequency oscillations; that is, onthe envelop of said radio-frequency oscillations. It is further evidentthat if the auxiliary system were tuned to the same wave length and wereidentical in all respects with the receiving the receiver would be zero.

v system proper,

tlal drop across resistances 13 and 13 would 85 that the oscillatingpotenthat the resultant current 1n It is essential therefore, foreflicient reception of signals, that the auxiliary system be tuned torespond very feebly to the waves originating at the sending station.When this condition obtains the response of the receiver 14 to thereceived .signals is practically independent of the auxiliary system.The auxiliary system, it will be seen, plays no part in reception ofsignals from the sending station, its function being solely to reduceand sub stantially eliminate interference from atmospheric or staticdisturbances in a manner now to be explained.

When a static, atmospheric or natural disturbance is incident' on awireless system, the

be equal and action thereon may be likened to the effect of a blow on atuningfork; that is, natural or characteristic damped oscillations areset up. The periodicity and damping of said natural oscillations aredependent on the constants of the vibrating system. In the organizationshown in Fig. 1, the receiving system and the auxiliary system areseparate and distinct as regards-natural oscillations, and thereforeeach oscillates in its own natural or characteristic damped period orperiods in response to the static dis-- turbance. It is well known thatthe natural oscillation of a loosely coupled circuit, such stantiallyindependent of the frequencies of the natural oscillations occurring incircuits are embodied in a simple antenna structure stantially eliminatestatic interference in the the resistance and inductance of circuit 4''cuits 4-4 as shown in Fig. 3. This'figure 125 as the circuit 4, has acharacteristic damping factor when R is the resistance of the circuitand L the inductance By means, therefore, of the adjustable resistanceelements 7 and 7 the circuits 4 and 4. may be adjusted to have the samecharacteristic damping factor, and therefore voltage drops acrossresistances 10 and 10 will be of similar form though not necessarily ofequal amplitudes. By adjustment of the relative amplifying powers of theamplifiers 11 and 11', the voltage drops across 13 and 13 may be madesubstantially equal. When this condition is attained the resultantcurrent in the receiver 14 is zero and the receiver is unaffected bynatural oscillations set up by static disturbances. It will be observedthat the'detectors 8 and 8 interposed between the common receiver 14 andthe antennae 1 and 1 make the voltage drops in resistances 10 and 10sub- 4 and 4 respectively.

Fig. 2 is a diagram of a second embodiment of my invention which differsfrom the organization shown in Fig. 1 in that the receiving antenna andthe auxiliary antenna having two branches, and repeating coils 18, 18,19, 19 are substituted for the reactance coils 9, 9', 12, 12 andnon-inductive resistances 10, 10, 13, 13 shown in Fig. 1. I

It will be observed that, in order to subreceiving device, it is of theutmost importance that the high frequency natural oscillations.occurring in the oscillation circuits 4 and4 shall be characterized bythe same damping factors. This condition is attained by loosely couplingsaid circuits to the antennae structures and adjusting said circuits tohave the same time constants, that is each of the oscillation circuits 4and 4 is so loosely coupled to the antennae as to render its naturaloscillations practically dependent on its own electrical constants 5alone and also adjusted to make 5 ll L L when R and are the resistanceand induc- 12o tance of c1rcu1t 4 respectively and R and L respectively.The same result may be obtamed without the useof the oscillationcirdiffers from Fig. 1 in the omission of condensers 6-.6' andresistances 7-7, the equality of the damping factors'in'this case beingattamed by adjustment of resistance 17 in the antenna circuit. Otherchanges will readily suggest themselves to those skilled in the art, andit Will therefore be understood that the invention is not limited to thespecific structures shown.

What is claimed is:

1. A wireless receiving system comprising a receiving antenna and anauxiliary antenna, a vacuum tube detector associated with said receivingantenna, a second vacuum tube detector associated with said auxiliaryantenna, a receiving device connected through said detectors with saidantenna, and means, including adjustable resistance elements forcontrolling the damping factors of waves set up in the two antennae,whereby the natural characteristic oscillations in said antennae,consequent upon a static disturbance, oppose and substantiallyneutralize each other as regards the said receiving device.

2. A wireless signaling system comprising a receiving antenna circuitproper, an auxiliary antenna circuit, a detecting de vice connected tosaid receiving antenna circuit, a second detecting device connected tosaid auxiliary antenna circuit, a receiving device differentiallyconnected to both of said detecting devices and means for amplifyingdisturbing oscillations in said circuits to approximately equalamplitude.

23. A wireless telegraph or telephone system comprising an antenna, asecond auxiliar antenna, an oscillation circuit including inductance,capacity and resistance elements connected to first named antenna, asecond oscillation circuit containing inductance, capacity andresistance elements connected to said auxiliary antenna, saidoscillation circuits being adjusted to have the same damping factors, adetecting device connected to said first named oscilla tion circuit, asecond detecting device connected to said second named oscillationcircuit, an amplifying device whose input side is connected to saidfirst named detecting device, asecond amplifying device Whose input sideis connected to saidsecond named detecting device and a receiving devicedifferentially connected to the output side of both of said amplifyingdevices.

4. A wireless telegraph or telephone system comprising an antenna,asecond auxiliary antenna, an oscillation circuit, includ ing inductance,capacity and resistance elements, connected to said first named antenna;a second oscillation circuit containing inductance, capacity andresistance elements connected with said auxiliary an tenna, a vacuumtube detector Whose input side is connected to said first namedoscillation circuit, a second vacuum tube detector Whose input side isconnected to said second named oscillation circuit, and a receivingdevice connected to the output side of both of said vacuum tubedetectors in such a manner that the effects upon said receiving deviceof oscillations occurring in said oscillation circuits are opposed andsubstantially neutralized.

5. A wireless telegraph or telephone system comprising an antenna, asecond auxiliary antenna, an oscillation circuit, including inductance,capacity and resistance elements, connected to said first named antenna,a second oscillation circuit containing inductance, capacity andresistance elements connected with said auxiliary antenna, a vacuum tubedetector Whose input side is operatively connected to said first namedoscillation circuit, a second vacuum tube detector whose input side isconnected to said second named oscillation circuit, a vacuum tubeamplifier Whose input sideis connected to said first named detector, asecond vacuum tube amplifier Whose input side is connected to saidsecond named detector; and a receiving device connected to the outputsides of both said amplifiers, the constants of said oscillationcircuits and the amplifying powers of said amplifiers being so adjustedthat the receiving device is unresponsive to simultaneous naturaloscillations occurring in said oscillation circuits.

6. A wireless system comprising a receiving antenna circuit proper, anauxiliaryantenna circuit, two oscillation circuits responsive,respectively to natural oscillations of said antennae circuits, adetecting device connected to one of said oscillation circuits, a seconddetecting device connected to the other of said oscillation circuits, areceiving device differentially connected to both of said detectors, andresistance elements included in said oscillation circuits and soadjusted that said receiving device is practically unaffected by thenatural oscillations of said antenna circuits Whileresponsive to signalswhich it is desired to receive.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses, this first day of September, A.D. 1915 LLOYD ESPENSCHIED.

